The present invention relates to a power train control apparatus and method for a vehicle provided with a power train having a power train mechanism for converting a driving power of an engine by an automatic transmission and transmitting it to a drive shaft.
In a vehicle which includes the system for converting a driving power of an engine by an automatic transmission and transmitting it to a drive shaft, a conventional control apparatus for controlling such a system by using a rotation speed of an input shaft of the automatic transmission is disclosed as "an Electronically-Controlled Automatic Transmission with "Hold" Mode Function in "an Automobile Technique, Vol.42, No.8, p1017, 1988". The control of an engine or automatic transmission is performed by providing a disk with an outer circumferential groove on the input shaft of the automatic transmission, detecting a cyclic period of rotation of the groove by using an electromagnetic pick-up, measuring the rotation speed of the input shaft, then calculating an input torque by using it, and obtaining a drive shaft torque. The detecting means is called as a turbine sensor. Further, there is another method in which a torque sensor for detecting the input shaft torque is used. Because the turbine sensor or the torque sensor is used to detect the rotation speed or the torque of the input shaft, the weight of the apparatus and its cost is increased.
An object of the invention is to provide an improved power train control apparatus and method, in which the rotation speed or the torque of the input shaft can be calculated and estimated accurately from input data such as an opening of a throttle valve and the engine rotation speed without using the turbine sensor and the torque sensor.
In order to attain the above object, the present invention is provided in a power train control apparatus comprising an engine, an automatic transmission having a torque converter, and a control unit for controlling the engine and the automatic transmission. The control apparatus is provided with calculating and estimating apparatus for calculating and estimating values of the input shaft torque and a gear ratio of the automatic transmission. Various characteristics of the engine and the torque converter are obtained in advance by experiments, such as the relationship between an engine torque and an engine speed, and that between a pump capacity coefficient data and a slip ratio of the torque converter. After that, data tables are made by using these characteristics, and control factors required to control the engine and the automatic transmission are calculated by a microcomputer in relation to the input shaft torque and the gear ratio.
By the construction described above, the rotation speed of the input shaft and the input shaft torque of the automatic transmission can be calculated and estimated in a simple manner by using the input data such as the throttle valve opening and the engine speed without decreasing accuracy.
The above and other advantages of the invention will become more apparent in the following description and the accompanying drawings in which like numerals refer to like parts.